History Of The Capacitor – The Modern Era

July 26, 2016 by Steven Dufresne 20 Comments

The pioneering years in the history of capacitors was a time when capacitors were used primarily for gaining an early understanding of electricity, predating the discovery even of the electron. It was also a time for doing parlor demonstrations, such as having a line of people holding hands and discharging a capacitor through them. The modern era of capacitors begins in the late 1800s with the dawning of the age of the practical application of electricity, requiring reliable capacitors with specific properties.

Leyden Jars

Marconi with transmitting apparatus, Published on LIFE [Public domain], via Wikimedia Commons

One such practical use was in Marconi’s wireless spark-gap transmitters starting just before 1900 and into the first and second decade. The transmitters built up a high voltage for discharging across a spark gap and so used porcelain capacitors to withstand that voltage. High frequency was also required. These were basically Leyden jars and to get the required capacitances took a lot of space.

Mica

In 1909, William Dubilier invented smaller mica capacitors which were then used on the receiving side for the resonant circuits in wireless hardware.

Early mica capacitors were basically layers of mica and copper foils clamped together as what were called “clamped mica capacitors”. These capacitors weren’t very reliable though. Being just mica sheets pressed against metal foils, there were air gaps between the mica and foils. Those gap allowed for oxidation and corrosion, and meant that the distance between plates was subject to change, altering the capacitance.

In the 1920s silver mica capacitors were developed, ones where the mica is coated on both sides with the metal, eliminating the air gaps. With a thin metal coating instead of thicker foils, the capacitors could also be made smaller. These were very reliable. Of course we didn’t stop there. The modern era of capacitors has been marked by one breakthrough after another for a fascinating story. Let’s take a look.

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Retrotechtacular: The Incredibly Difficult Task Of Copying A Document

July 20, 2016 by Al Williams 57 Comments

It seems hard to imagine, but in the early part of the 20th century, there weren’t a lot of great options for creating copies of documents. The most common method was to use carbon paper to create multiple copies at once from a typewriter or a line printer. All that changed with a company called Haloid. Never heard of them? They later became the Xerox company.

The underlying technology dates back to 1938 (invented by a physicist who was also a lawyer). In 1944, they produced a practical copier and shortly thereafter sold the rights to Haloid. The Haloid company originally made photographic copy machines that used wet chemistry.

In 1959, the Xerox 914 (so called because it could copy a 9″ x 14″ document) came on the scene (that’s it, below). The 650 pound copier could make seven copies per minute and came with a fire extinguisher because it had a tendency to burst into flames. If you didn’t want to spend the $27,500 price tag, you could rent for only $25/month (keep in mind that in 1959, $25 would buy about 25 pounds of T-bone steaks). You can see a commercial for the 914 in the video below.

In the commercial, you’ll see them make a big deal out of the fact that the print was dry. That’s because a lot of previous machines used actual photographic processes with wet chemistry. Obviously, that also took special paper.

Even Further Back

If the copier didn’t exist until recently, how did people make copies before? Turns out there were lots of ways to make copies of varying degrees of bad quality or extreme trouble. In some sense, the best copies were made by scribes just writing down a second copy of things. There were a variety of machines that would capture what you wrote and make a copy by mechanical or other means. A polygraph (not the lie detecting kind) allowed Thomas Jefferson to write letters and make a copy. The machine moved a pen to match the movements of the author’s pen, thus making a near perfect copy. With a few adjustments, this became the pantograph which not only does the same job, but also can shrink or enlarge the copy. Carbon paper was widely used to make multiple copies of handwritten and typewritten documents.

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History Of The Capacitor – The Pioneering Years

July 12, 2016 by Steven Dufresne 31 Comments

The history of capacitors starts in the pioneering days of electricity. I liken it to the pioneering days of aviation when you made your own planes out of wood and canvas and struggled to leap into the air, not understanding enough about aerodynamics to know how to stay there. Electricity had a similar period. At the time of the discovery of the capacitor our understanding was so primitive that electricity was thought to be a fluid and that it came in two forms, vitreous electricity and resinous electricity. As you’ll see below, it was during the capacitor’s early years that all this changed.

The history starts in 1745. At the time, one way of generating electricity was to use a friction machine. This consisted of a glass globe rotated at a few hundred RPM while you stroked it with the palms of your hands. This generated electricity on the glass which could then be discharged. Today we call the effect taking place the triboelectric effect, which you can see demonstrated here powering an LCD screen.

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Don Eyles Walks Us Through The Lunar Module Source Code

July 5, 2016 by Gregory L. Charvat 53 Comments

A couple weeks ago I was at a party where out of the corner of my eye I noticed what looked like a giant phone book sitting open on a table. It was printed with perforated green and white paper bound in a binder who’s cover looked a little worse for the wear. I had closer look with my friend James Kinsey. What we read was astonishing; Program 63, 64, 65, lunar descent and landing. Error codes 1201, 1202. Comments printed in the code, code segments hastily circled with pen. Was this what we thought we were looking at? And who brings this to a party?

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EV History: The Lightning Precedes The Thunder

June 27, 2016 by Moritz Walter 39 Comments

In 1988, a bunch of engineers from Hotzenwald, Germany, came together and decided that it is time for the future of mobility: A new, more modern and environmentally friendly car should put an end to fossils and emissions while still being fun to drive. “It should become a new kind of car. Smaller, lighter, cleaner – and more beautiful” is how future CEO Thomas Albiez described his mission. For the first time in automotive history, this series car would be designed as an all-electric vehicle from the start and set a new standard for mobility. The project was given the codename “Hotzenblitz” (“Hotzen Bolt”) to indicate how the idea came to them: Like a lightning bolt. The snarky regional term also came with a double meaning: Imaginary lightning bolts, used for insurance fraud.

hotzenblitz_chassis — Hotzenblitz frame construction (origin unknown, image source)

Unnoticed by the rest of the world, they founded Hotzenblitz Mobile. Industrial Designer Harold Schurz was contracted to design the chassis for the Hotzenblitz, which was then modeled into a prototype chassis. The self-funded team moved fast. An external motorsports company helped to develop the tubular steel frame, and soon their vision took on shape. After the team had fitted a motor and transmission into the frame, CEO Thomas Albiez himself installed the traction battery and drive train. The team felt confident with the result, and in July 1990, during an open house day in the office, they somewhat spontaneously decided to call Green Tech entrepreneur and chocolate mogul Alfred Ritter.

Alfred Ritter had experienced financial losses after the Chernobyl Disaster. Many agricultural regions, including several hazelnut plantations that were vital to Alfred’s chocolate business, were irreversibly lost to the fallout contamination. It was then when he turned to the green energy business, founding the Paradigma group to manufacture solar collector systems and pellet heaters. When Thomas and the team called, Alfred jumped on the idea of an electric car. In the same year, Alfred Ritter and his sister Marli Hoppe-Ritter became shareholders in the company and helped to finance the future of the Hotzenblitz.

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The Man Who Didn’t Invent The Personal Computer

May 23, 2016 by Brian Benchoff 45 Comments

[John Blankenbaker] did not invent the personal computer. Museums, computer historians, and authors have other realities in mind when they say [John]’s invention, the KENBAK-1, was the first electronic, commercially available computer that was not a kit, and available to the general population.

In a way, it’s almost to the KENBAK’s detriment that it is labelled the first personal computer. It was, after all, a computer from before the age of the microprocessor. It is possibly the simplest machine ever sold and an architecturally unique machine that has more in common with the ENIAC than any other machine built in the last thirty years..

The story of the creation of this ancient computer has never been told until now. [John], a surprisingly spry octogenarian, told the story of his career and the development of the first personal computer at the Vintage Computer Festival East last month. This is his story of not inventing the personal computer.

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Volkswagen Beetle – The Most Hackable Car

May 3, 2016 by Bryan Cockfield 118 Comments

If you build a better mousetrap, the world will beat a path to your door. Of course it helps if your mousetrap is reliable, simple, cheap, and easy to work on. In the car world, look no further than arguably the most successful, and most hackable, car in history: the Volkswagen Type 1, more commonly known as the Beetle. The ways in which this car was modified to suit the needs of a wide range of people over its 65-year-long production run proves that great design, ease of use, and simplicity are the keys to success, regardless of the project or product.

Built by Ferdinand Porsche in 1930’s Germany, the Beetle was designed to be a car for anyone and everyone. Its leader at the time wanted a true “people’s car” (i.e. “Volkswagen”) that was affordable for a German family, could reliably travel at sustained highway speeds on the new German autobahns, and easily be repaired by its owners. The car features an air-cooled engine for simplicity and cost savings: no radiator, water pump, or coolant, plus reduced overall complexity. The engine can be easily removed by disconnecting the fuel line, the throttle cable, and the four bolts that hold it to the transaxle. The entire body is held on to the chassis by eighteen bolts and is also easy to remove by today’s standards. There’s no air conditioning, no power steering, and a rudimentary heater of sorts for the passenger cabin that blows more hot air depending on how fast the engine is running. But possibly the best example of its simplicity is the fact that the windshield washer mechanism is pressurised with air from the over-inflated spare tire, eliminating the need to install another piece of equipment in the car.

It’s not too big of a leap to realize how easily hackable this car is. Even Volkswagen realized this and used the platform to build a number of other vehicles: the Type 2 (otherwise known as the bus, van, hippie van, Kombi, etc.) the eclectic Karmann Ghia, and the Types 3 and 4. Parts of the Type 1 were used to build the Volkswagen 181, commonly referred to as “the Thing”. Ferdinand Porsche also used design elements and other parts of the Type 1 to build the first Porsche, essentially making a souped-up Beetle. The rear-engine, rear-wheel drive layout of modern Porsches is a relic of this distant Beetle cousin. But the real magic is what people started doing to the Beetles in their backyards in the ’60s and 70s: turning them into buggies, off road machines, race cars, and hot rods that are still used today.

At some point around this time, a few people realized that the Beetle was uniquely suited to off-road racing. The type of suspension combined with the rear-engine, rear-wheel-drive layout meant that even without four-wheel drive, this car could excel in desert racing. There are still classes in this race for stock Beetles and modified Beetles called Baja Bugs.

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